Precut metal lines

ABSTRACT

Embodiments of the present invention provide a method for cuts of sacrificial metal lines in a back end of line structure. Sacrificial Mx+1 lines are formed above metal Mx lines. A line cut lithography stack is deposited and patterned over the sacrificial Mx+1 lines and a cut cavity is formed. The cut cavity is filled with dielectric material. A selective etch process removes the sacrificial Mx+1 lines, preserving the dielectric that fills in the cut cavity. Precut metal lines are then formed by depositing metal where the sacrificial Mx+1 lines were removed. Thus embodiments of the present invention provide precut metal lines, and do not require metal cutting. By avoiding the need for metal cutting, the risks associated with metal cutting are avoided.

FIELD OF THE INVENTION

The present invention relates generally to semiconductor fabrication,and more particularly, to precut metal lines.

BACKGROUND

As the fabrication techniques for semiconductor devices has progressed,manufacturers have been placing an increasingly larger number of deviceson a chip by increasing the integration density of semiconductordevices. Accordingly, a critical dimension (CD) in a design rule isgradually reduced in order to increase the circuit density.

In order to increase the circuit density, it is necessary to reduce thesizes of elements inside the semiconductor devices and reduce thelengths and widths of interconnections which couple the elementstogether. Moreover, the resistances of interconnections must be small sothat electric signals can be transferred with minimal loss within thesemiconductor devices through interconnections having narrow widths.

In a typical integrated circuit, there may be many metallization layersand interconnecting via layers formed in a back end of line (BEOL)interconnect structure. The BEOL interconnect structure connects variousdevices (e.g. transistors, capacitors, etc.) to form functionalcircuits. During fabrication, it is necessary to form cuts andconnections of metal lines to create the desired connectivity toimplement a given design. As critical dimensions continue to shrink,this can be challenging. It is therefore desirable to have improvementsto address the aforementioned challenges.

SUMMARY

Embodiments of the present invention provide a method for cuts ofsacrificial metal lines in a back end of line structure. SacrificialMx+1 lines are formed above metal Mx lines. A line cut lithography stackis deposited and patterned over the sacrificial Mx+1 lines and a cutcavity is formed. The cut cavity is filled with dielectric material. Aselective etch process removes the sacrificial Mx+1 lines, preservingthe dielectric that fills in the cut cavity. Precut metal lines are thenformed by depositing metal where the sacrificial Mx+1 lines wereremoved. Thus, embodiments of the present invention provide precut metallines, and do not require metal cutting. By avoiding the need for metalcutting, the risks associated with metal cutting are avoided.

In a first aspect, embodiments of the present invention provide a methodof forming a semiconductor structure, comprising: forming a plurality ofsacrificial Mx+1 lines over a plurality of metal Mx lines; depositing adielectric layer over the plurality of sacrificial Mx+1 lines; forming acut cavity in one sacrificial Mx+1 line of the plurality of sacrificialMx+1 lines; forming a dielectric region in the cut cavity; removing theplurality of sacrificial Mx+1 lines to form a plurality of Mx+1 linecavities; and filling the plurality of Mx+1 line cavities with a metalto form a plurality of metal Mx+1 lines.

In a second aspect, embodiments of the present invention provide amethod of forming a semiconductor structure, comprising: forming aplurality of sacrificial Mx+1 lines over a plurality of metal Mx lines;depositing a dielectric layer over the plurality of sacrificial Mx+1lines; depositing an organic planarization layer on the dielectriclayer; depositing a resist layer on the organic planarization layer;forming a cavity in the resist layer and organic planarization layer;removing the resist layer; depositing a conformal spacer layer on theorganic planarization layer; performing an anisotropic etch on theconformal spacer layer to form an aperture spacer; forming a cut cavityin one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines;forming a dielectric region in the cut cavity; removing the plurality ofsacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; andfilling the plurality of Mx+1 line cavities with a metal to form aplurality of metal Mx+1 lines.

In a third aspect, embodiments of the present invention provide a methodof forming a semiconductor structure, comprising: forming a plurality ofsacrificial Mx+1 lines over a plurality of metal Mx lines; depositing adielectric layer over the plurality of sacrificial Mx+1 lines; forming acut cavity in one sacrificial Mx+1 line of the plurality of sacrificialMx+1 lines; forming a dielectric region in the cut cavity; removing theplurality of sacrificial Mx+1 lines to form a plurality of Mx+1 linecavities; depositing a via cut lithography stack; patterning an openingin the via cut lithography stack; forming a via cavity that exposes oneMx metal line of the plurality of metal Mx lines; removing the via cutlithography stack; and filling the plurality of Mx+1 line cavities andvia cavity with a metal to form a plurality of metal Mx+1 lines and avia.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of thepresent teachings and, together with the description, serve to explainthe principles of the present teachings.

Certain elements in some of the figures may be omitted, or illustratednot-to-scale, for illustrative clarity. The cross-sectional views may bein the form of “slices”, or “near-sighted” cross-sectional views,omitting certain background lines which would otherwise be visible in a“true” cross-sectional view, for illustrative clarity.

Often, similar elements may be referred to by similar numbers in variousfigures (FIGs) of the drawing, in which case, typically the last twosignificant digits may be the same, the most significant digit being thenumber of the drawing figure (FIG). Furthermore, for clarity, somereference numbers may be omitted in certain drawings.

FIG. 1 is a semiconductor structure at a starting point for embodimentsof the present invention.

FIG. 2 is a semiconductor structure after a subsequent process step ofdepositing a sacrificial layer.

FIG. 3 is a semiconductor structure after subsequent process steps ofdepositing a resist layer and patterning the resist layer.

FIG. 4 is a semiconductor structure after subsequent process steps ofpatterning the sacrificial layer and removing the resist layer.

FIG. 5 is a side view of a semiconductor structure after a subsequentprocess step of depositing a dielectric layer over the sacrificial Mx+1lines.

FIG. 6 is a side view of a semiconductor structure after a subsequentprocess step of planarizing the dielectric layer.

FIG. 7 is a semiconductor structure after subsequent process steps ofdepositing and patterning a line cut lithography stack.

FIG. 8 is a semiconductor structure after a subsequent process step offorming a cut cavity in a sacrificial Mx+1 line.

FIG. 9 is a semiconductor structure after a subsequent process step ofremoving the line cut lithography stack.

FIG. 10 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step ofremoving the resist layer.

FIG. 11 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step ofdepositing a conformal spacer layer.

FIG. 12 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step ofperforming an anisotropic etch to form an aperture spacer.

FIG. 13 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step offorming a cut cavity in a sacrificial Mx+1 line.

FIG. 14 is a semiconductor structure after a subsequent process step offorming a dielectric region in the cut cavity.

FIG. 15 is a semiconductor structure after a subsequent process step ofremoving the sacrificial Mx+1 lines.

FIG. 16 is a semiconductor structure after subsequent process steps ofdepositing and patterning a via cut lithography stack.

FIG. 17 is a semiconductor structure after a subsequent process step offorming a via cavity that exposes an Mx metal line.

FIG. 18 is a semiconductor structure after a subsequent process step ofremoving the via cut lithography stack.

FIG. 19 is a semiconductor structure after a subsequent process step offorming metal Mx+1 lines.

FIG. 20 is the semiconductor structure of FIG. 19 as viewed along lineB-B′.

FIG. 21 is a flowchart indicating process steps for embodiments of thepresent invention.

DETAILED DESCRIPTION

Exemplary embodiments will now be described more fully herein withreference to the accompanying drawings, in which exemplary embodimentsare shown. It will be appreciated that this disclosure may be embodiedin many different forms and should not be construed as limited to theexemplary embodiments set forth herein. Rather, these exemplaryembodiments are provided so that this disclosure will be thorough andcomplete and will fully convey the scope of this disclosure to thoseskilled in the art.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of this disclosure.For example, as used herein, the singular forms “a”, “an”, and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. Furthermore, the use of the terms “a”, “an”, etc.,do not denote a limitation of quantity, but rather denote the presenceof at least one of the referenced items. It will be further understoodthat the terms “comprises” and/or “comprising”, or “includes” and/or“including”, when used in this specification, specify the presence ofstated features, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof.

Reference throughout this specification to “one embodiment,” “anembodiment,” “embodiments,” “exemplary embodiments,” or similar languagemeans that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the present invention. Thus, appearances of the phrases “in oneembodiment,” “in an embodiment,” “in embodiments” and similar languagethroughout this specification may, but do not necessarily, all refer tothe same embodiment.

The terms “overlying” or “atop”, “positioned on” or “positioned atop”,“underlying”, “beneath” or “below” mean that a first element, such as afirst structure, e.g., a first layer, is present on a second element,such as a second structure, e.g. a second layer, wherein interveningelements, such as an interface structure, e.g. interface layer, may bepresent between the first element and the second element.

FIG. 1 is a semiconductor structure 100 at a starting point forembodiments of the present invention. Semiconductor structure 100 showsa back-end-of-line (BEOL) wiring structure having a plurality of metallines 106, which are formed in a dielectric layer 102. In embodiments,dielectric layer 102 may be comprised of SiOC (silicon oxycarbide). Inembodiments, the metal lines 106 are comprised of copper. Inembodiments, each metal line 106 is surrounded on the sides and bottomby a barrier layer 104. This serves to prevent diffusion of the metal.In embodiments, the barrier layer 104 is comprised of tantalum and/ortantalum nitride. A capping layer 105 may be deposited on the tops ofthe metal lines 106. In embodiments, the capping layer 105 may becomprised of SiN (silicon nitride). The metal lines 106 are referred toas Mx lines, where “x” denotes a particular metallization level. Belowmetal lines 106 are metal lines 103. Thus, metal lines 103 are referredto as Mx−1 metal lines. The metal lines may be formed usingindustry-standard techniques, including, but not limited to, barrierdeposition, metal seed layer deposition, and a metal plating process,followed by a planarization process. In embodiments, an etch stop layer110 is deposited over the dielectric layer 102, covering the metal lines106. In embodiments, the etch stop layer 110 is comprised of aluminumoxide (Al2O3).

FIG. 2 is semiconductor structure 100 after a subsequent process step ofdepositing a sacrificial layer 112 over the semiconductor structure. Thesacrificial layer 112 is deposited on the etch stop layer 110. Inembodiments, the sacrificial layer 112 may be comprised of SiN, and maybe deposited by plasma enhanced chemical vapor deposition (PECVD).Amorphous silicon can also be used as a sacrificial material.

FIG. 3 is semiconductor structure 100 after subsequent process steps ofdepositing and patterning a resist layer (lithography stack) 114, thusforming a patterned lithography stack. The patterning may beaccomplished using industry-standard lithographic methods, including,but not limited to, self-aligned double patterning (SADP), orself-aligned quad patterning (SAQP).

FIG. 4 is semiconductor structure 100 after subsequent process steps ofpatterning the sacrificial layer and removing the resist layer. Thisforms sacrificial “dummy” Mx+1 lines 116 on the semiconductor structure.This may be achieved by anisotropically etching the sacrificial layer112 of FIG. 3, stopping on etch stop layer 110, as to remove the portionof the sacrificial layer that is not covered by the patterned resistlayer in order to form sacrificial “dummy” lines 116, and then removingthe resist layer 114. In some embodiments, etch stop layer 110 may alsobe removed. Note that both Mx and Mx+1 are illustrated as a regular setof unidirectional parallel lines at each level, with Mx+1 perpendicularto Mx.

FIG. 5 is a side view of semiconductor structure 100 after a subsequentprocess step of depositing a dielectric layer 118 over the sacrificialMx+1 lines as viewed along line A-A′ of FIG. 4. In embodiments, thedielectric layer 118 may be comprised of silicon oxycarbide (SiOC). Thedielectric layer may be deposited using a plasma-enhanced chemical vapordeposition (PECVD) process. In embodiments, due to the conformal natureof the dielectric layer 118, air gaps 120 may be formed in between eachsacrificial line 116. The air gaps have a dielectric constant ofapproximately 1, and thus can serve to improve circuit performance inregards to high speed signals that propagate through BEOL layers.

FIG. 6 is a side view of semiconductor structure 100 after a subsequentprocess step of planarizing the dielectric layer 118 such that it issubstantially flush with the sacrificial lines 116. In embodiments, theplanarization is performed with a chemical mechanical polish (CMP)process. The air gaps 120 may be preserved during this process (asshown), or in some embodiments, may be partially opened (not shown).

FIG. 7 is semiconductor structure 100 after subsequent process steps ofdepositing and patterning a line cut lithography stack 122. The line cutlithography stack 122 may include an organic planarization layer (OPL)followed by a layer of photoresist (referred to as “resist”). Inembodiments, the OPL can include a photo-sensitive organic polymercomprising a light-sensitive material that, when exposed toelectromagnetic (EM) radiation, is chemically altered and thusconfigured to be removed using a developing solvent. For example, thephoto-sensitive organic polymer may be polyacrylate resin, epoxy resin,phenol resin, polyamide resin, polyimide resin, unsaturated polyesterresin, polyphenylenether resin, polyphenylenesulfide resin, orbenzocyclobutene (BCB).

A plurality of voids 124 are patterned in the lithography stack 122. Thevoids 124 each expose a region of a sacrificial line 116, as well assome of the dielectric region 118. The dielectric layer 118 and thesacrificial lines 116 are comprised of different materials, allowingselective etch techniques to remove the portions of the sacrificiallines 116 that are exposed through the voids 124, without removing theexposed dielectric regions 118. Thus, the tolerances of the position andsizing of each void 124 is relaxed, enabling easier manufacturing andimproved product yield.

FIG. 8 is semiconductor structure 100 after a subsequent process step offorming a cut cavity 126 in a sacrificial Mx+1 line. As statedpreviously, the dielectric layer 118 and the sacrificial lines 116 arecomprised of different materials, allowing selective etch techniques toremove the portions of the sacrificial lines 116. Thus, exposed regionsof sacrificial lines 116 are removed, exposing the etch stop layer 110below, and forming a cut cavity 126.

FIG. 9 is semiconductor structure 100 after a subsequent process step ofremoving the line cut lithography stack (122 in FIG. 7). The lithographystack may be removed using industry-standard techniques, thus revealingthe pattern of sacrificial lines 116 with cut cavities 126 at locationswhere the replacement (metal) lines are to be separated.

FIG. 10 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step ofremoving the resist layer of line cut lithography stack 122 (see FIG.7), exposing an underlying organic planarization layer (OPL). Thus FIG.10 follows from FIG. 7, but provides additional process steps to furthercontrol the size of the cut cavities, as will be shown in the followingfigures. Voids 124 are formed in the OPL 128 to expose regionssacrificial lines 116.

FIG. 11 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step ofdepositing a conformal spacer layer 130. In embodiments, the conformalspacer layer 130 is comprised of carbon, and may be deposited via anatomic layer deposition process. In embodiments, the conformal spacerlayer has a thickness ranging from about 2 nanometers to about 5nanometers. A recessed portion 132 is formed over the voids 124 in theOPL.

FIG. 12 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step ofperforming an anisotropic etch to form an aperture spacer 134. Inembodiments, the anisotropic etch may include a reactive ion etch (RIE)process. The anisotropic etch removes most of the conformal spacerlayer, except for the remaining portion, which is aperture spacer 134.The aperture spacers 134 have a segment thickness D1. In embodiments, D1ranges from about 2 nanometer to about 8 nanometers. The aperturespacers further restrict the opening prior to removing a portion of thesacrificial lines 116 to have a length D2, thus enabling smaller cutcavities. In embodiments, D2 may range from about 5 nanometers to about30 nanometers.

FIG. 13 is a semiconductor structure in accordance with an alternativeembodiment of the present invention after a subsequent process step offorming a cut cavity in a sacrificial Mx+1 line. As stated previously,the dielectric layer 118 and the sacrificial lines 116 are comprised ofdifferent materials, allowing selective etch techniques to remove theportions of the sacrificial lines 116. The carbon spacer may then beselectively etched away.

FIG. 14 is a semiconductor structure after a subsequent process step offorming a dielectric region 118A in the cut cavity. From FIG. 14forward, the process is similar for both the embodiment shown in FIGS.1-9, and for the alternative embodiment with additional steps shown inFIGS. 10-13. As shown in FIG. 14, additional dielectric material 118A isdeposited in each cut cavity. A planarization process may follow, suchthat the dielectric regions 118A are substantially planar withsacrificial lines 116 and dielectric regions 118. This can beaccomplished by a chemical mechanical polish (CMP) process and/or ananisotropic RIE etch back. Dielectric regions 118A and dielectricregions 118 are preferably comprised of the same material. Hence, inembodiments, dielectric regions 118A may also be comprised of SiOC.

FIG. 15 is a semiconductor structure after a subsequent process step ofremoving the sacrificial Mx+1 lines. This may be accomplished using aselective etch process, such that dielectric regions 118 and 118A remainintact.

FIG. 16 is a semiconductor structure after subsequent process steps ofdepositing and patterning a via cut lithography stack 136. The via cutlithography stack 136 may contain an OPL layer, antireflective layer,and a resist layer. Using patterning, voids 138 are formed in the viacut lithography stack 136. The voids are formed over an area where thesacrificial lines 116 have been removed, thus revealing a portion ofcapping layer 105 of a perpendicularly oriented Mx line disposed in themetallization layer below. Depending on a given design, it is desirableto, at certain locations, form vias that interconnect to neighboringmetallization levels. Thus, voids are formed where it is desirable toform a via between an Mx line and an Mx+1 line.

FIG. 17 is a semiconductor structure after a subsequent process step offorming a via cavity that exposes an Mx metal line. The region ofcapping layer (see 105 of FIG. 16) is removed using a selective etchprocess. For example, if the dielectric layer 118 is SiOC, and thecapping layer 105 is SiN, then a variety of selective etch techniquescan be used to selectively remove the capping layer 105. Embodiments ofthe present invention may use other materials for the dielectric andcapping layer, so long as selective etching of the materials to eachother is possible.

FIG. 18 is a semiconductor structure after a subsequent process step ofremoving the via cut lithography stack (136 of FIG. 17). This exposescapping regions 105 where no via is to be formed, while Mx line 106 isexposed in an area where a via is to be formed.

FIG. 19 is a semiconductor structure after a subsequent process step offorming metal Mx+1 lines. In embodiments, this may include anelectroplating process. The process may include depositing one or morebarrier layers and/or seed layers (not shown). Then, a fill metal (suchas copper) is deposited in the location where the sacrificial Mx+1 linespreviously occupied, forming metallization lines 142. The dielectricregion 118A separates metallization line 142A from metallization line142A′. Thus, metallization lines 142A and 142A′ are precut, as they areformed with the cuts already in place, and so metal cutting is avoided.Metallization line 142B has a via that connects to the Mx level, as willbe further described in the next figure.

FIG. 20 is the semiconductor structure of FIG. 19 as viewed along lineB-B′. As can be seen, Mx+1 metal line 142B connects to Mx metal line106. When Mx+1 metal line 142B was formed, the Mx line 106 was exposed,since its capping layer was removed (see 106 in FIG. 18). Hence, theprocess in accordance with embodiments of the present inventionsimplifies fabrication by avoiding metal cuts, and also integrates viaconnectivity into the metallization process.

FIG. 21 is a flowchart 200 indicating process steps for embodiments ofthe present invention. In process step 250, sacrificial lines areformed. In embodiments, the sacrificial lines are comprised of siliconnitride. In process step 252, a dielectric layer is deposited. Inembodiments, the dielectric layer is comprised of SiOC. In process step254, a line cut lithography stack is deposited (see 122 of FIG. 7). Inprocess step 256, the sacrificial lines are cut (see FIG. 9). In processstep 258, additional dielectric is deposited in the cut cavities (see118A of FIG. 14). In process step 260, the sacrificial lines are removed(see FIG. 15). In embodiments, the etch stop layer (110 in FIG. 1) isalso removed. In process step 262, a via cavity lithography stack isdeposited (see 136 of FIG. 16). In process step 264, selected M(x) linesare opened in locations where a via between the M(x) and M(x+1) levelsis to be formed (see 140 of FIG. 17). In process step 266, M(x+1) metallines are formed (see 142 of FIG. 19). The processes disclosed hereinmay then be repeated to make multiple metallization levels. In someembodiments, there may be 10 or more levels. Once the BEOL stack iscomplete, industry-standard techniques for additional processes such aspackaging and test may be used to complete fabrication of the integratedcircuit.

While the invention has been particularly shown and described inconjunction with exemplary embodiments, it will be appreciated thatvariations and modifications will occur to those skilled in the art. Forexample, although the illustrative embodiments are described herein as aseries of acts or events, it will be appreciated that the presentinvention is not limited by the illustrated ordering of such acts orevents unless specifically stated. Some acts may occur in differentorders and/or concurrently with other acts or events apart from thoseillustrated and/or described herein, in accordance with the invention.In addition, not all illustrated steps may be required to implement amethodology in accordance with the present invention. Furthermore, themethods according to the present invention may be implemented inassociation with the formation and/or processing of structuresillustrated and described herein as well as in association with otherstructures not illustrated. Therefore, it is to be understood that theappended claims are intended to cover all such modifications and changesthat fall within the true spirit of the invention.

What is claimed is:
 1. A method of forming a semiconductor structure,the method comprising: forming a plurality of sacrificial Mx+1 linesover a plurality of metal Mx lines; depositing a dielectric layer overthe plurality of sacrificial Mx+1 lines; forming a cut cavity in onesacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines;forming a dielectric region in the cut cavity; removing the plurality ofsacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; andfilling the plurality of Mx+1 line cavities with a metal to form aplurality of metal Mx+1 lines.
 2. The method of claim 1, wherein forminga plurality of sacrificial Mx+1 lines comprises: depositing asacrificial layer over the plurality of metal Mx lines; depositing alithography stack on the sacrificial layer; patterning the lithographystack to form a patterned lithography stack; removing a portion of thesacrificial layer that is not covered by the patterned lithographystack; and removing the lithography stack.
 3. The method of claim 1,wherein depositing a dielectric layer comprises depositing SiOC.
 4. Themethod of claim 3, further comprising planarizing the dielectric layer.5. The method of claim 4, wherein planarizing the dielectric layercomprises performing a chemical mechanical polish process.
 6. The methodof claim 1, wherein filling the plurality of Mx+1 line cavities withmetal comprises filling the plurality of Mx+1 line cavities with copper.7. A method of forming a semiconductor structure, the method comprising:forming a plurality of sacrificial Mx+1 lines over a plurality of metalMx lines; depositing a dielectric layer over the plurality ofsacrificial Mx+1 lines; depositing an organic planarization layer on thedielectric layer; depositing a resist layer on the organic planarizationlayer; forming a cavity in the resist layer and organic planarizationlayer; removing the resist layer; depositing a conformal spacer layer onthe organic planarization layer; performing an anisotropic etch on theconformal spacer layer to form an aperture spacer; forming a cut cavityin one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines;forming a dielectric region in the cut cavity; removing the plurality ofsacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; andfilling the plurality of Mx+1 line cavities with a metal to form aplurality of metal Mx+1 lines.
 8. The method of claim 7, whereindepositing a conformal spacer layer comprises depositing carbon.
 9. Themethod of claim 8, wherein depositing carbon is performed with an atomiclayer deposition process.
 10. The method of claim 7, wherein forming aplurality of sacrificial Mx+1 lines comprises: depositing a sacrificiallayer over the plurality of metal Mx lines; depositing a lithographystack on the sacrificial layer; patterning the lithography stack to forma patterned lithography stack; removing a portion of the sacrificiallayer that is not covered by the patterned lithography stack; andremoving the lithography stack.
 11. The method of claim 7, whereindepositing a dielectric layer comprises depositing SiOC.
 12. The methodof claim 11, further comprising planarizing the dielectric layer. 13.The method of claim 12, wherein planarizing the dielectric layercomprises performing a chemical mechanical polish process.
 14. Themethod of claim 7, wherein filling the plurality of Mx+1 line cavitieswith metal comprises filling the plurality of Mx+1 line cavities withcopper.
 15. A method of forming a semiconductor structure, the methodcomprising: forming a plurality of sacrificial Mx+1 lines over aplurality of metal Mx lines; depositing a dielectric layer over theplurality of sacrificial Mx+1 lines; forming a cut cavity in onesacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines;forming a dielectric region in the cut cavity; removing the plurality ofsacrificial Mx+1 lines to form a plurality of Mx+1 line cavities;depositing a via cut lithography stack; patterning an opening in the viacut lithography stack; forming a via cavity that exposes one Mx metalline of the plurality of metal Mx lines; removing the via cutlithography stack; and filling the plurality of Mx+1 line cavities andvia cavity with a metal to form a plurality of metal Mx+1 lines and avia.
 16. The method of claim 15, wherein forming a plurality ofsacrificial Mx+1 lines comprises: depositing a sacrificial layer overthe plurality of metal Mx lines; depositing a line cut lithography stackon the sacrificial layer; patterning the line cut lithography stack toform a patterned line cut lithography stack; removing a portion of thesacrificial layer that is not covered by the patterned line cutlithography stack; and removing the patterned line cut lithographystack.
 17. The method of claim 15, wherein depositing a dielectric layercomprises depositing SiOC.
 18. The method of claim 17, furthercomprising planarizing the dielectric layer.
 19. The method of claim 18,wherein planarizing the dielectric layer comprises performing a chemicalmechanical polish process.
 20. The method of claim 19, wherein fillingthe plurality of Mx+1 line cavities with metal comprises filling theplurality of Mx+1 line cavities with copper.